There has been proposed an object positioning detection apparatus that uses both a millimeter-wave radar and a stereo camera. With object detection apparatuses, in general, the following may occur: being unable to detect an object even though it is located within a detection target area (i.e., non-detection); detecting an object in a detection target area when none is present (i.e., an erroneous detection); or managing to detect an object, but detecting a plurality of objects as a single object (i.e., an erroneous merged detection) or detecting a single object as a plurality of objects (i.e., erroneous separated detections).
In an effort to avoid such detection failures, detection thresholds are adjusted, for example. With millimeter-wave radars, such detection thresholds are set with respect to wave reflection intensity, and with stereo cameras, they are set with respect to parallax extraction amount.
However, while it might be possible to prevent non-detection and erroneous detections through such detection threshold adjustments alone, it would be difficult to completely prevent erroneous merged detections or erroneous separated detections.
With respect to the problem above, Patent literature 1 discloses an object detection apparatus that prevents erroneous separated detections. Specifically, with this object detection apparatus, a set of detection target object candidates is first detected using stereo images taken with a stereo camera. Next, based on the luminance value of each pixel within the respective image regions corresponding to the detection target object candidates, a threshold is altered, the threshold being one that is used in determining whether or not to merge a plurality of detection target object candidates and treat them as one detection target object candidate.
In Patent Literature 2, in order to reduce the incidence of erroneous separated detections and erroneous merged detections, an anticipated detection target object site is used as a criterion for determining whether or not to merge a set of detection target object candidates detected by a millimeter-wave radar and treat them as one detection target object (i.e., it is used as a merge condition).